Spark plug



Feb. 2, 1937. 1.. .LMCKONE SPARK PLUG Filed July 17; 1955 @217 0.1- ZeozZ/l lc K0226 Patented Feb. 2, 1937 UNITED STATES PATENT OFFICE SPARKPLUG Application July 17, 1935, Serial No. 31,804

6 Claims.

This invention relates to a spark plug and more particularly to a sparkplug wherein the electrodes define a spark gap of varying width.

In the usual spark plug employed in internal combustion engines, thesurfaces defining the spark gap are parallel to each other to provide aspark gap of constant width. Such an arrangement does not compensate forthe varying intensities of the spark at different speeds of the engine.At low speed, for instance, when the mixture is rich and the compressionlow, a fat spark would be desirable, whereas at high speed, with themixture lean and compression high, the .spark is then weaker, so that anarrower spark gap would be desirable.

I have now found that greater ignition efficiency can be obtained underthese conditions by providing a spark gap of varying width. With such aspark gap, when the engine is operating at low speed and the mixture isrich, the ignition coil can give. a fat spark that will more efficientlyignite the overly rich mix. However, at high speeds, when the mix islean and compression is high, the spark is then weaker due to lowsaturation of the primary windings in the ignition coil and with myvarying width spark gap, the spark finds a narrower gap to jump across.

It is therefore an object of this invention to provide a spark plughaving a spark gap of varying width, whereby the ignition efficiency ofthe spark plug is increased.

It is a further important object of this invention to provide a sparkplug wherein the electrode wires present convergent surfaces defining aspark gap of varying width to compensate for varying intensities ofspark at different engine speeds.

Other and further important objects of this invention will be apparentfrom the disclosures in the specification and the accompanying drawing'.

This invention (in a preferred form) is illustrated in the drawing andhereinafter more fully described.

On the drawing:

Figure 1 is an elevational view, partly in section, of a spark plugembodying the principles of my invention.

Figure 2 is a fragmentary elevational view taken substantially along theline II-II of Fig. 1.

Figure 3 is a sectional view taken substantially on the line IIIIII ofFig. 1.

Figure 4 is a fragmentary sectional view of a modified form of myinvention.

Figure 5 is a further modified form of my invention.

As shown on the drawing:

The reference numeral indicates generally a spark plug embodying'theprinciples of my l5 of the wire.

The skirt i3 is provided with an extension t6, angularly offsettherefrom and connected thereto by a neck portion ll of reduced crosssectional area. The purpose of reducing the cross sectional area of themetal connecting the extension I6 with the skirt I3 is to reduce theamount of heat flowing from the extension IE to the skirt l3 k and thusconcentrate the heat to a greater extent in said extension.

A second electrode wire I8 is secured at one end in the extension l6 andextends in the plane of the wire l4 and at an angle thereto provide a 25spark gap, indicated at I9, of varying Width. The angle between theelectrode I8 and the electrode I4 is not a right angle, as is customaryin heretofore known spark plug constructions, so that the longitudinalsurface of the wire I 8 forms a small acute angle with the plane surfaceof the wire end l5. There is thus provided a spark gap of varying widththat permits the spark to jump across at the wider or at the narrowerpoint depending upon the condition of the ignition U coil.

In Fig. 4, a laterally extending electrode is secured at one end in thebottom portion of a skirt 2i and projects at right angles to a coreelectrode 22. The free end of the electrode 28 40 is beveled as at 23 toprovide a spark gap 24 of varying width between the plane lower end ofthe electrode 22 and the tapered fiat surface 23 of the electrode 20.

In Fig. 5, there is a reversal of parts, in that the vertical electrode25 is provided with a tapered or beveled flat end face 26 and thelaterally extending electrode 21 projects at right angles to the axis ofthe electrode 25 to provide a spark gap 28 of varying width between thetwo electrodes.

It will thus be apparent that all of these various forms of my inventionembody the same principle of a varying width spark gap. The variation inthe width of the spark gap at various points will depend upon manyfactors but in general the minimum width will be in the neighborhood of0.020 inch and the maximum width in the neighborhood of 0.032 inch. Thisvariation in width permits an automatic compensation for the variationsin the intensity of the ignition coil current at different enginespeeds. Thus, when the engine speed is slow and the mixture is rich, thespark being more intense can jump through the greater distance providedby the varying spark gap, and when the engine speed is high and theintensity of the spark weak, the spark can jump across the narrow width.

I am aware that many changes may be made and numerous details ofconstruction may be varied through a wide range without departing fromthe principles of this invention, and I, therefore, do not purposelimiting the patent granted hereon otherwise than necessitated by theprior art.

I claim as my invention:

1. In a spark plug, a pair of angularly disposed electrodes lying insubstantially the same plane, a flat end surface of one electrode and atapered fiat surface on the other electrode defining a spark gap ofvarying width.

2. In a spark plug, a pair of electrode wires, one of said wiresextending axially of the plug and having a beveled fiat end face and theother of said wires extending substantially at right angles to the firstwire.

3. In a spark plug, a pair of spaced electrode wires, one of said wiresextending axially of said plug and having a flat end surface, and theother of said wires extending at an angle to said first wire to presenta surface convergent with respect to said flat end surface for defininga spark gap of varying width.

4. A spark plug comprising a coaxial electrode wire having a normalplane end face, a threaded skirt surrounding said wire and having anextension beyond said wire end face, said extension being joined to saidskirt by a neck portion of reduced cross sectional area, and a secondelectrode wire secured in said extension and extending in non-parallelrelation to the plane of said end face to define a spark gap of varyingwidth.

5. A spark plug comprising a shell having a depending skirt portion withan extension below the botom of the skirt, said extension being joinedto the skirt by a neck portion of reduced cross-sectional area, anelectrode Wire secured in said extension below the neck portion thereofand extending transversely along the bottom of the plug, a secondelectrode wire extending axially within the shell of the plug, an endsurface of one electrode and a longitudinal surface of the otherelectrode defining a spark gap of varying width.

6. A spark plug comprising a shell having a depending skirt portion withan extension below the bottom of the skirt, said extension being joinedto the skirt by a neck portion of reduced cross-sectional area, and anelectrode wire secured at its end in said extension below the neckportion thereof.

LEO J. McKONE.

